Method of producing absorbent or resilient felt



Patented Feb. 13, 1934 UNITED STATES PATENT OFFICE METHOD OF PRODUCING ABSORBENT R RESILIENT FELT No Drawing. Application August 19, 1931 Serial No. 558,185

8 Claims.

The invention relates to a method of producing kinked, curled, or crimped fibres from finished or prepared cellulosic fibrous pulp material and to the production of a felted material having substantial bulk and absorbency, and resiliency, and to the production of a felted material having substantial resiliency and waterproof qualities.

An object of the invention is the production of curled fibre by means of a treating solution having the characteristic of pronounced physicochemical reactivity or drasticity for effecting curling or crinkling of the fibres.

Another object is the provision of a method employing a treating solution of a certain chemical capable of producing curling, kinking or crimping of prepared fibres.

Another object is the production of a felted product of substantial absorbency and resiliency.

A further object is to produce such a product which has a marked afiinity for waterproofing agents.

Another object is the production of a resilient waterproof relatively non-absorbent felted product.

The invention contemplates treating finished or prepared cellulosic fibrous pulp material with a solution of sodium sulfide to produce curling of the fibres. Other terms descriptive of the v effect of the sodium sulfide solution upon the prepared fibres, are kinked, crimped, crinkled, or rufiied.

I have discovered that sodium sulfide in solution will produce pronounced curling of the finished fibres treated with such solution.

Microscopic examination indicates that sodium sulfide solution causes a thickening of the fibre wall. In the process of thickening irregularities of the fibre wall are emphasized or magnified, thereby causing the fibre to twist, curl and crinkle.

In the felting or piling up of these twisted fibres countless spaces of capillary function are formed, thereby imparting to the felted product its commercial valueof absorbency, extreme bulk, capability of being impregnated and resiliency.

The treatment with the sodium sulfide solution may be carried out in any suitable type of equipment, and with or without the presence of other chemical or materials.

Sodium sulfide solution alone is effective to produce curling of the prepared fibres for the production of absorbent and resilient felt.

While it is not desired to restrict the invention to any particular concentration of sodium sulfide in the solution, I have found that sodium l sulfide solutions of approximately 4% to 35% concentration, are effective in producing curling of the finished fibres for the production of grades of absorbent and resilient felt for many uses.

While it is not desired to limit the invention as to time of treatment of the produced or prepared pulp with the sodium sulfide solution, I may say that from a few seconds to approximately sixty minutes is sufiicient to: effect substantial curling of the fibres, depending upon the dryness of raw material, mechanical means for impregnation, temperature and concentration of chemical. A suitable temperature range may be approximately from 0 C. to 110 C.

While it is not desired to limit the invention to any given temperature or pressure, it may be stated that a satisfactory product for ordinary use may be obtained at atmospheric pressure and temperature around 20 C. Cooling eifects the same result as increasing concentration, and heat or pressure increases the rate of saturation and consequently cuts down necessary treating time.

Finished or prepared fibres or pulp as herein mentioned means fibrous pulp material which has already been produced by treatment with treating solutions for the purpose of neutralizing and dissolving the cementitious inter-cellular substances and separating and cleansing the cellulose fibres, by any of the well known processes. The present invention is directed to the further treatment of the finished or prepared pulp produced by any of the well known pulp producing processes, to produce a product in which the fibres are curled or crimped by the sodium sulfide solution treatment, and to produce an absorbent and resilient felt product.

This absorbent and resilient felt product has marked aflinity for attaching to itself precipitated waterproofing agents such as rosin, aluminum hydrate, copper hydrate, zinc hydrate, etc., and when so treated that these substances are deposited on the surface of the fibres in insoluble form, a springy waterproof relatively non-absorbent product is the result,a waterproof prodlOO uct which may be compressed and released many times without losing its resiliency.

I claim:

1. The method comprising treating finished or 9 prepared cellulosic fibrous pulp material with so- 1 dium sulfide solution, producing kinking, curling, or crimping of the pulp fibres which had been previously finished or cleansed of cementitious inter-cellular substances.

2. The method comprising treating finished or l prepared cellulosic fibrous pulp with sodium sulfide solution, producing a kinking, curling, or crimping of the pulp fibres which had been previously finished or cleansed of cementitious inter-cellular substances, and forming the curled pulp fibre into an absorbent and resilient felt.

3. The method of producing kinked, curled, or crimped cellulosic fibrous material including treating finished or prepared fibres, from which cementitious inter-cellular substances have been neutralized and dissolved, with a treating solution containing only sodium sulfide as the active kinking, curling or crimping agent.

4. The method comprising treating finished or prepared cellulosic fibrous pulp material with sodium sulfide solution of from about 4% to 35% concentration, producing kinking, curling, or crimping of the pulp fibres which had been previously finished 0r cleansed of cementitious intercellular substances.

5. The method according to claim 1 including precipitating on the surfaces of the kinked, curled, or crimped, fibres in aqueous suspension, a waterproofing material such as rosin, aluminum hydrate, copper hydrate, zinc hydrate or the like, producing a resilient waterproof felt product.

6. The method comprising treating finished or prepared cellulosic fibrous pulp material with sodium sulfide solution of about 4% to 35% concentration, for a period of from about E; minute to 60 minutes, producing kinking, curling or crimping of the pulp fibres which had been previously finished or cleansed of cementitious intercellular substances.

.7. The method comprising treating finished or prepared. cellulosic fibrous pulp material with sodium sulfide solution of about 4% to 35% con- 

